The present invention relates to a semiconductor device and in particular, to a power conversion component built in an electric conversion apparatus, such as general inverter apparatus, numerically controlled machine tool, or air conditioner.
In general, an inverter apparatus that is applied to a variable-speed device for a motor is composed of a power element for electric conversion, a drive circuit for controlling and driving the power element, a protection circuit, and a control circuit for generally controlling these components. A power conversion device having a semiconductor device called "intelligent power module" (hereafter referred to as "IPM") has been commercially available, and is formed of an integrated package including, in the above components, the power element for converting a direct current into an alternate current, the drive circuit, and the protection circuit.
FIG. 10 is a block diagram showing a configuration of a circuit in a conventional inverter apparatus. The inverter apparatus is composed of a converter 1 connected to a two- or three-phase alternate power supply to convert an alternate current into a direct current; an electrolytic capacitor 2 for smoothing; an IPM 3; a control circuit formed of a central processing unit 6 (CPU.ROM) including a buffer 4, a controller 5, and a memory; a power supply circuit for the IPM 3 and control circuit, formed of a switching transistor 7, transformers 8, 9, and a switching regulator 10; and a current transformer CT installed between an output of the IPM 3 and a motor M.
The IPM 3 is integrally composed of a three-phase inverter 11 composed of a power element and providing an output connected to the motor M; a predriver 12 for controlling and driving the inverter 11; a protect circuit 13; a sensor 14 for detecting an overcurrent; a sensor 15 for detecting overheating; a braking power element 16 and a resistor 17 that are used to provide deceleration control for the motor M; and a predriver 18 for controlling and driving the braking power element 16.
A control signal from the control circuit to the IPM 3 is supplied from the buffer 4 to the predrivers 12, 18 via a photocoupler, and an alarm signal issued when the sensor 14 or 15 detects an overcurrent or overheated condition is supplied from the protect circuit 13 to the buffer 4 via the photocoupler. In addition, an output from the current transformer CT is connected to the controller 5.
The current transformer CT detects an output current flowing from the IPM 3 to the motor M in order to return this current to the controller 5 for various controls. The current transformer CT has three through-holes therein, and is provided in the inverter apparatus in such a manner that wires or bars that act as output-current lines from the inverter 11 are inserted through these through-holes.
In the inverter apparatus with the configuration as described above, a direct voltage converted by the converter 1 is converted by the inverter 11 into an alternate voltage supplied to the motor M. In the inverter 11, bridges are assembled by using IGBTs (Insulated Gate Bipolar Transistors) and diodes, and the IGBTs chopping-control a direct current to allow an alternate current to consequently flow through the motor. By varying the frequency of this alternate current, the rotational speed of the motor can be varied.
In addition, an inverter output current detected by the current transformer CT is input to the controller 5, which controls such that the waveform of the output current will not be distorted or the output voltage does not exceed a predetermined value.
FIG. 11 is a block diagram showing a power conversion circuit in a conventional inverter apparatus. The power conversion circuit is composed of two modules, that is, the converter 1 and the IPM 3 including the inverter 11. Module terminals 21 to 25, which are shown by a circle, are provided for the converter 1 as I/O terminals, and module terminals 26 to 30 are provided for the IPM 3. In addition, terminal blocks R, S, T, P1, P2, N, U, V and W, which are shown by large black circles, are provided as I/O terminals for the converter 1 and inverter apparatus including the IPM 3.
The module terminals 21 to 30 of the converter 1 and IPM 3 are connected to the corresponding terminal blocks, and these connections are carried out by, for example, screwing copper bars to the blocks. The connections between the converter 1 and the inverter 11, that is, the connections between the terminal blocks P1 and P2 and between the module terminals 25 and 27 are also carried out by screwing copper bars to the blocks.
However, the current transformer built into the conventional inverter apparatus to monitor an output current is relatively larger than the other components and thus requires a large installation space, thereby hindering the development of more compact inverter apparatuses. In addition, since the wires or bars acting as output current lines must be inserted through the current transformer, the number of assembly steps is so large that the process becomes complicated.
In addition, since the module terminals and the terminal blocks are connected together by screwing the wire rods, such as copper bars, the apparatus requires a large number of set screws for connections, a complex wiring pattern, and a large number of assembly steps. In addition, an installation space must be provided for the wiring, and this constitutes a constraint on space-saving efforts.
The present invention has been made in view of these problems, and an object of the invention is to provide a power conversion component that can reduce a space for the incorporated devices and that can reduce requirements for both wiring space and the number of assembly steps.
Further objects and advantages will be apparent from the following description of the invention